Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. There are many different metals that can be made into sheet metal, such as aluminum, brass, copper, steel, tin, nickel and titanium. Conventional sheet metals and alloys deform via the formation of dislocations, i.e., plastic work. For these conventional metals, sheet metal fabrication processes can mostly be placed into two categories—forming and cutting. Forming processes are those in which the applied force causes the material to plastically deform, but not to fail. So what one would be doing is one would be introducing plastic work into the alloy as one would form it into thinner and thinner sheets. So it is cold worked. Such processes are able to bend or stretch the sheet into the desired shape. Cutting processes are those in which the applied force causes the material to fail and separate, allowing the material to be cut or removed.
On the other hand, for a bulk-solidifying amorphous alloy (also referred to as bulk metallic glass (BMG)), the sheet forming processes of the conventional crystalline metals are generally not applicable as amorphous alloys do not deform by the formation of dislocations. They fail through the formation of shear bands, which are, in general, the sort of process that are not really desirable.
A conventional method for making a BMG sheet requires casting a amorphous metal alloy at or above the melting temperature of the amorphous metal alloy, freezing the molten amorphous metal alloy in a sheet mold to form a sheet, and then using a cutting tool to remove the gate portion of the cast sheet and shape the cast sheet into the desired final geometry. However, casting requires melting and cooling of the amorphous metal alloy in a sheet mold, and this can cause uncontrolled amount of amorphicity in the BMG sheet. Furthermore, the post-processing cost for removing the gate and runner overflow and shaping the cast sheet into the desired final sheet geometry can be quite high. Therefore, new methods for making BMG sheets that overcome the above mentioned limitations of the casting process are desirable.